Newest thing I can think of is Owl City, though it’s more bubbly than Frou Frou, I think.
I always thought The Postal Service was kind of similar… but that’s not new at all… XD
I get the feeling that some of Maaya Sakamoto’s songs are a little similar. (Yoko Kanno composes a lot of her songs)I guess Utada too, but that’s straying a bit… and is Japanese

Of course there’s also Imogen’s own albums. Ellipse (the newest one) and Speak for Yourself (the one before it) are a lot more similar Frou Frou than her first album, iMegaphone, though.